Objectives: A. Syntheses and structure-antitumor relationships studies among the alpha, beta-unsaturated cyclopentanone related derivatives are in progress. B. Further synthesis of novel bifunctional steroidal alpha-methylene-gamma-lactones and related derivatives as potential anticancer agents are in progress. C. Continuing syntheses of new/novel mono- to poly-alkylating functional helenalin related derivatives as potential cytotoxic and antitumor agents will be shown. D. Biochemical mechanism of action of helenalin related sesquiterpene lactones will be investigated.